Die casting with ultrasonic vibration



May 4, 1965 E, w. REARWIN 3,181,211

DIE CASTING WITH ULTRASONIC VIBRATION Filed May 16, 1962 2 Sheets-Sheet1 FIG. I

POWER SUPPLY IN VEN TOR. EARLE W. REARWIN Jul $7 d M ATTORNEYS y 4, 1965E. w. REARWIN 3,

DIE CASTING WITH ULTRASONIC VIBRATION Filed May 16, 1962 2 Sheets-Sheet2 United States Patent 3,181,211 DIE CASTING WITH ULTRASGNlC VHERATKGNEarle W. Rearwin, High Point, N.C., assignor to Adams- MillisCorporation, High Point, N.C., a corporation of North Carolina Filed May16, I962, Ser. Nan-195,078 6 Claims. (Cl. 22-68) This invention relatesto die casting and, more particularly, to improvements in theconstruction of the die halves utilized in a die casting machine.

It isthe general object of the invention to provide a method and meansof producing stronger and more dense products in the use of die castingmachines.

A more specific object of the invention is to provide a die constructionfor die casting machines which incorporates an ultrasonic vibratorhaving a tip projecting through an opening in one of the die halves andinto the die cavity so as to act upon the molten metal therein toproduce the desired results set forth in the general object of thisinvention.

The drawings show preferred embodiments of the invention and suchembodiments will be described, 'but it will be understood that variouschanges may be made from the constructions disclosed, and that thedrawings and description are not to be construed as defining or limitingthe scope of the invention, the claims forming a part of thisspecification being relied upon for that purpose.

Of the drawings:

FIG. 1 is a rather diagrammatic elevational view of that portion of aconventional die casting machine to which the improvements of thepresent invention may be added;

FIG. 2 is an enlarged plan view of the die assembly featuring thepresent invention;

FIG. 3 is a still further enlarged horizontal crosssectional view of theejector-half of the die assembly shown in FIG. 2; and

FIG. 4 is a view generally similar to FIG. 3 but it illustrates amodified mounting arrangement for the ultrasonic vibrator.

Referring now to FIG. 1, it will be observed that the die castingmachine to which the presently improved die construction maybe appliedincludes a movable platen and a stationary platen 12 which respectivelysupport the ejector-half 14 and the cover-half 16 of the dieconstruction or assembly. In keeping with conventional die castingmachine construction, the movable platen I0 is mounted on a plurality oftie bars 18, 18 for closing movement toward the right which engages thedie halves 14 and 16 and for return movement toward the left to theposition shown which is the die open position.

As will be mentioned again, when the die halves are engaged or closedthey cooperate to define a die cavity to which molten metal isintroduced through a plunger sleeve 20 in the cover-half of the die. Aplunger 22 is arranged to be reciprocated within the said sleeve by anhydraulic motor 24 so that molten metal introduced through an opening 26to the sleeve in advance of the plunger 22 can be rammed into the diecavity under desired pressure. In further keeping with conventional diecasting machine operating techniques, an electrical con trol panel 2% ismounted on the machine to provide switches that control solenoidoperated valves that in turn control the operation of the hydraulicmotor 24 for the plunger and an hydraulic motor (not shown) forreciprocating the movable platen 10 and its associated ejectorhalf 14 ofthe die. In one normal sequence of die casting machine operation, aswitch at the control panel 28 is closed to effect closing of the diehalves and then a switch is operated to advance the plunger 22 to move acharge ice of molten metal into the die cavity. Then, after apreselected time period, the plunger is retracted and the die halves arethen opened. In this sequence of operations, the high-frequency vibratorincorporated in the die construction is preferably energized whentheplunger is advanced and then de-energized when the plunger isretracted.

The improved die constructions illustrated in FIGS. 2, 3 and 4- includemany conventional parts. Referring to the ejector-half 14, and as bestshown in FIGS. 2 and 3, it is part of a subassembly which includes ananchor plate 39 which is detachably secured to the movable platen 10.Mold base plates 32, 32 are secured to the anchor plate 30 and projectforwardly therefrom to support the ejectorhalf 14. Accordingly, when theplaten It) is moved forwardly and rearwardly the ejector-half, the baseplates and the anchor plate move with it. In the advanced or forwardposition of the platen 10, the ejector-half 14 en gages the cover-half16 in face-to-face relationship and they cooperate to define the entiredie cavity which is indicated generally in FIG. 2 by the referencenumber 34. This cavity includes the runner portion 36 which in keepingwith conventional practice is ordinarily defined wholly within theejector-half l4 and which is connected to the product cavity portion 38at a gate 40, the product cavity 38 being defined partly in theejector-half 14 and partly in the cover-half 16. In further keeping withconventional practice, cavity retainer blocks or inserts 42., 42 areprovided, one in each die half, to facilitate the machining of thedesired cavity surfaces.

In further keeping with conventional techniques, an ejector plate 44 isprovided for the ejector-half 14, the ejector plate being secured to aback-up plate 46 by a series of machine screws such as the screw 48. Aplurality of ejector pins 5%, 5th mounted in the ejector plate 44 andseated against the back-up plate 46 extend into suitable openings in theejector-half 14 with their extending ends nearly flush with the surfaceof the cavity 38 formed in the ejector-half. Generally similar push pins52, 52 extend from the ejector-plate and back-up plate through theejector-half 14 to engage the front face of the coverhalf when the diehalves are engaged. These push pins thereby thrust the ejector plate andback-up plate assembly relatively rearwardly with respect to theejector-half to properly position the ends of the ejector pins 5t), 50relative to the cavity.

When the die has been cast, and the ejector-half 14 is retracted withthe platen 10, the anchor plate 30 and the base plates 32, 32, itcarries the cast product and runner rearwardly with it. Near the end ofthe rearward travel of this assembly, stop pins 54, 54 engage a fixed Istop and prevent further rearward movement of the backup plate 46 andthe ejector plate 44- to eject the casting from the ejector-half. Morespecifically, the stop pins 54, 54 at their front ends engage the rearsurface of the back-up plate 46 and they have shoulders 56, 56 seated insuitable apertures in the anchor plate 30 so that they will carry theejector plate and back-up plate forwardly with the anchor plate and theejector-half of the die. The said stop pins also have rearwardlyextending reduced diameter portions 58, 58 which slidably projectthrough the anchor plate 30 and the movable platen 10 to engage a stopplate (not shown) as the ejector-half assembly is retracted. Thisthrusts the stop pins 54, 54 relatively forwardly and the ejector pins50, 50 are thrust into the cavity area to eject the casting. All of theaforedescribed portion of the die construction is conventional.

As has been mentioned before, the improved die construction of thisinvention incorporates a high-frequency vibrator which is so constructedand arranged asto act upon the molten metal in the die cavity with theresult that the improved final product is obtained. Preferably;

the vibrations produced in the molten metalare of ultrasonic frequency.

One type of device suitable for the purpose of producing the ultrasonicvibration desired is that known as the sonifier manufactured by BransonInstruments, Inc. of Stamford, Connecticut. This device comprises apower supply unit and a sonic converter or transducer. A description ofthe sonifier is published in the winter 1961- 1962 edition of UltrasonicNews, a copyrighted publication of Branson Instruments, Inc. The powersupply unit is shown schematically and designated generally by thereference number 66 in FIG. 1, and it is an electronic instrumentcapable of converting a 50 or 60 cycle alternating current signal at 115volts to radio frequency power at approximately 20,000 cycles persecond. The power output at radio frequency is transmitted to thetransducer which is preferably a device of piezoelectric material or amagnetostrictive material which converts the high-frequency electricalenergy to mechanical vibratory energy at the same frequency. Thepreferred piezoelectric material is lead zirconate titanate which hasthe ability to deliver great amounts of mechanical energy at highefiiciency from a full wave electrical energy input. When amagnetostrictive material is used, nickel or nickel alloys arepreferred. As shown in the drawings, the electrical signal from thepower supply unit 60 is transmitted to the transducer which is indicatedgenerally by the reference numeral 62- through a conductor 64.

As best shown in FIGS. 2, 3 and 4, the transducer 62 comprises arelatively large diameter body portion 66, the piezoelectric ormagnetostrictive block 68 and a tapered or reduced diameter horn 70 onthe said block which terminates in a tip 72. The transducer can bemounted on either the ejector-half or the cover-half of the die, but forconvenience in installation and general access, .it is preferablymounted on the ejector-half 14. It will be noted with reference to FIG.3 that the anchor plate 30, the back-up plate 46, the ejector plate 44,the ejector-half 14 and its cavity retainer block 42 are all providedwith registering passages for the installation of the transducer and foraccess thereto. It will be noted further that the tip 72 of thetransducer horn 70 is located in flush relationship with the surface ofthe cavity block 42 which cooperates to define the cavity 34.Preferably, the transducer is so located that its vibratory tip willengage the molten metal in the runner 36 closely adjacent the gate 40 tothe product cavity 38.

The mounting of the transducer is by means of a nodal ring 74 whichembraces the piezoelectric block 68 adjacent the horn 70 and which issecured in the ejector-half 14 by means of a plurality of screws such asthe screw 76 which extend through the ejector-half and into the diecavity block 42. The nodal ring 74 is located on the transducer at itsnull point, i.e., the point at which no expansion or contraction of thematerial occurs as a result of the electrical signal which it receives.The said material does expand and contract on each side of the ring 74,the expansion and contraction on the horn side being concentrated due tothe reduced diameter configuration of the horn so that the tip 72 willbe vibrated over a relatively substantial distance which may be on theorder of .005 inch. It is important to observe that the transducer ismounted solely by means of the ring 74 and that its other parts havefreedom of movement Within the openings provided in the die elementswith which they are associated. Thus, the vibration effected at theultrasonic frequencies causes no noise due to mounting.

An alternative mounting arrangement for the transducer is shown in FIG.4, and the alternative mount is sometimes preferred. In the saidalternative form of mounting, a generally cylindrical member 80 iswelded to a plate 82 to project forwardly therefrom and the said plateis secured to a slightly modified ejector plate 44a as by machine screws84, 84. A front annular plate 86 is secured to the cylindrical member 80and the nodal ring 88 is mounted thereon by rearwardly extending screwssuch as the screw 90.

In the aforedescribed alternative mounting for the transducer, it moveswith the ejector plate and the ejector pins. When the die halves areclosed, the vibrating tip 72 of the transducer is flush with the cavitysurface as shown in full lines in FIG. 4, but when the die halves areopened to eject the casting, the tip 72 projects forwardly from the faceof the ejector-half 14 as shown by the broken lines in FIG. 4. This hasthe advantage of ejecting any chips or spray that may be trapped betweenthe wall of the die and the horn of the transducer and thereby wedgingof the vibrating transducer is fully avoided.

The invention claimed is:

l. A die construction for a die casting machine and comprising acover-half and an ejector-half which engage to define a cavity forcasting a metal product and a runner attached thereto at a gate, the diecasting machine being of the type which has means for mounting the saiddie halves for relative movement so that they can be selectively engagedor closed and then opened respectively to receive molten metal and toeject the formed product and its runner, one of the, said die halvesbeing provided with an opening extending therethrough and communicatingwith the cavity, an electro-mechanical transducer disposed within saidopening for movement therein and having a reduced end substantiallyflush with a surface of said one die half at the cavity, the saidtransducer being connectible with a source of radio frequency electricalenergy and comprising a material capable of changing its dimensionresponsive to and in keeping with the frequency of such electricalenergy to vibrate its reduced end, a nodal ring embracing saidtransducer between its ends at a point of minimum vibration, and meansfor mounting said ring within said opening to support the transducertherein.

2. A die construction as set forth in claim 1 and wherein the openingthrough the said one die half is arranged to communicate with the cavityin the runner portion thereof adjacent the gate.

3. A die construction for a die casting machine and comprising acover-half and an ejector-half which engage to define a cavity forcasting a metal product and a runner attached thereto at a gate, the diecasting machine being of the type which has means for mounting the saiddie halves for relative movement so that they can be selectively engagedor closed and then opened respectively to receive molten metal and toeject the formed product and its runner, the said ejector-half beingprovided with an opening extending therethrough and communicating withthe cavity, an electro-mechanical transducer disposed within saidopening for movement therein and being of generally cylindricalconfiguration and having a reduced diameter end substantially flush witha surface of said ejector-half at the cavity, the said transducercomprising a piezoelectric material connectible with a source of radiofrequency electrical energy and responsive thereto and in keeping withits frequency to change its dimension and thereby vibrate the reduceddiameter end, a nodal ring embracing the transducer between its ends ata point of minimum vibration, and means for mounting said ring withinthe opening to support the transducer therein.

4. A die-construction for a die casting machine and comprising acover-half and an ejector-half which engage to define a cavity forcasting a metal product and a runner attached thereto at a gate, the diecasting machine being of the type which has means for mounting the saiddie halves for relative movement so that they can be selectively engagedor closed and then opened respectively to receive molten metal and toeject the formed product and its runner, the said ejector-halfcomprising a subassembly which includes an ejector plate movable alimited distance relative to other parts of the ejector-half to eject afinished casting, and said other parts having an opening therethroughcommunicating with the cavity, an electro-meehanical transducer disposedWithin said opening for movement therein, the said transducer beingconnectible with a source of radio frequency electrical energy andcomprising a material capable of changing its dimension responsive toand in keeping with the frequency of such electrical energy whereby thetransducer is vibrated, and means on said ejector plate supporting saidtransducer with one of its ends substantially flush with a surface ofsaid ejector-half at the cavity when the die halves are closed and forprojecting the said one end of the transducer into the cavity area whenthe die halves are open to eject a casting.

5. A die construction for a die casting machine and comprising acover-half and an ejector-half which engage to define a cavity forcasting a metal product and a runner attached thereto at a gate, the diecasting machine being of the type which has means for mounting the saiddie halves for relative movement so that they can be selectively engagedor closed and then opened respectively to receive molten metal and toeject the formed product and its runner, the said ejector-halfcomprising a subassembly which includes an ejector plate movable alimited distance relative to other parts of the ejector-half to eject afinished casting, and said other parts having an opening therethroughcommunicating with the cavity, an

electro-mechanical transducer disposed within said opening for movementtherein and being of generally cylindrical configuration and having areduced diameter end, the said transducer comprising a piezoelectricmaterial connectible with a source of radio frequency electrical energyand responsive thereto and in keeping with its frequency to change itsdimension and thereby vibrate its reduced diameter end, and means onsaid ejector plate including a ring embracing said transducer to supportit With its reduced diameter end substantially flush with a surface ofthe ejector-half at the cavity when the die halves are closed and forprojecting the reduced diameter end into the cavity area when the diehalves are open to eject a casting.

6. A die construction as set forth in claim 5 wherein the openingthrough the said ejector-half communicates with the cavity in the runnerportion thereof adjacent the gate.

References ited by the Examiner Weber et al.: Sound Waves ImproveDiecasting Quality, Foundry, February, 1961, pp. 69-71.

MICHAEL V. BRINDISI, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

1. A DIE CONSTRUCTION FOR A DIE CASTING MACHINE AND COMPRISING ACOVER-HALF AND AN EJECTOR-HALF WHICH ENGAGE TO DEFINE A CAVITY FORCASTING A METAL PRODUCT AND A RUNNER ATTACHED THERETO AT A GATE, THE DIECASTING MACHINE BEING OF THE TYPE WHICH HAS MEANS FOR MOUNTING THE SAIDDIE HALVES FOR RELATIVE MOVEMENT SO THAT THEY CAN BE SELECTIVELY ENGAGEDOR CLOSED AND THEN OPENED RESPECTIVELY TO RECEIVE MOLTEN METAL AND TOEJECT THE FORMED PRODUCT AND ITS RUNNER, ONE OF THE SAID DIE HALVESBEING PROVIDED WITH AND OPENING EXTENDING THRETHROUGH AND COMMUNICATINGWITH THE CAVITY, AND ELECTRO-MECHANICAL TRANSDUCER, DISPOSED WITHIN SAIDOPENING FOR MOVEMENT THEREIN AND HAVING A REDUCED END SUBSTANTIALLYFLUSH WITH A SURFACE OF SAID ONE DIE HALF AT THE CAVITY, THE SAIDTRANSDUCER BEING CONNECTIABLE WITH A SOURCE OF RADIO FREQUENCYELECTRICAL ENERGY AND COMPRISING A MATERIAL CAPABLE OF CHANGING ITSDIMENSION RESPONSIVE TO AND IN KEEPING WITH THE FREQUENCY OF SUCHELECTRICAL ENERGY TO VIBRATE ITS REDUCED END, A NODAL RING EMBRACINGSAID TRANSDUCER BETWEEN ITS ENDS AT A POINT OF MINIMUM VIBRATION, ANDMEANS FOR MOUNTING SAID RING WITHIN SAID OPENING TO SUPPORT THETRANSDUCER THEREIN.